Copolymers and films thereof

Abstract

Novel copolymers having a density (D) in the range 0.895-0.910 g/cm3, a melt index MI2 (2.16 kg, 190° C.) in the range of 0.01-6 g/10 min, a Compositional Distribution Branch Index (CDBI) in the range 55-85%, and a sealing initiation temperature (SIT) and density (D) satisfying the relationship SIT≤(A×D)−B wherein A is 800° C.×cm3/g and B is 650° C., wherein the SIT (° C.) is determined on a 70 μm film at 0.5N/15 mm and D Is in units of g/cm3 are disclosed. The copolymers may be suitably prepared by use of metallocene catalyst systems and may be used in film applications, in particular as sealing layers for packaging applications.

The invention claimed is: 
     
       1. A copolymer of ethylene and an alpha-olefin, said copolymer having
 (a) a density (D) in the range 0.895-0.910 g/cm 3 , 
 (b) a melt index MI 2  (2.16 kg, 190° C.) in the range of 0.01-6 g/10 min, 
 (c) a Compositional Distribution Branch Index (CDBI) in the range 55-85%, and 
 (d) a sealing initiation temperature (SIT) and density (D) satisfying the relationship
   SIT≤( A×D )− B  
 
 
 wherein A is 1700° C.×cm 3 /g and B is 1469° C., and 
 wherein the SIT (° C.) is determined on a 70 μm film at 0.5N/15 mm and D is in units of g/cm 3 , and 
 (e) a Crystallizable Species Fraction below 55° C. (CSF55)≥12%. 
 
     
     
       2. A copolymer according to  claim 1  having a Compositional Distribution Branch Index (CDBI) in the range 65-85%. 
     
     
       3. A copolymer according to  claim 1  having a density in the range 0.901-0.907 g/cm 3 . 
     
     
       4. A copolymer according to  claim 1  having a melt index MI 2  (2.16 kg, 190° C.) in the range of 0.05-5 g/10 min. 
     
     
       5. A copolymer according to  claim 1  having a sealing initiation temperature (SIT)<72° C. 
     
     
       6. A copolymer according to  claim 1  having a molecular weight distribution (Mw/Mn) greater than 3.4 and less than 4.5. 
     
     
       7. A copolymer according to  claim 1  wherein the alpha-olefin is 1-hexene. 
     
     
       8. A copolymer according to  claim 1  prepared in the presence a metallocene catalyst system. 
     
     
       9. A copolymer according to  claim 8  wherein the metallocene catalyst system comprises a monocyclopentadienyl metallocene complex. 
     
     
       10. A copolymer according to  claim 1  exhibiting a powder compressability (C) as follows:
   %  C <(− A′×D )+ B′ 
 
 wherein D is the density in kg/m 3  and A′=1 and B′=928. 
 
     
     
       11. A copolymer according to  claim 1  exhibiting a powder compressability (C) as follows:
   %  C <(− A×D )+ B′ 
 
 wherein D is the density in kg/m 3  and wherein A′=0.5 and B′=468. 
 
     
     
       12. A copolymer according to  claim 1  having a Compositional Distribution Branch Index (CDBI) in the range 65-85%. 
     
     
       13. A copolymer according to  claim 1  having a sealing initiation temperature (SIT)<65° C. 
     
     
       14. A copolymer according to  claim 1  having a Crystallizable Species Fraction below 55° C. (CSF55)≥15%.